A treatment of implanting an intraocular lens (IOL) in a patient's eye may be conducted. For example, in a cataract surgery, after a crystalline lens is removed from inside the patient's eye, an intraocular lens (IOL) is inserted into the patient's eye. For determining the power of the intraocular lens, eye characteristics data such as the eye axial length and the cornea curvature (cornea refractivity) of the targeted eye are measured in advance, and based on the obtained eye characteristics data, the power of the intraocular lens is determined in accordance with a known IOL calculation formula. Particularly, in order to properly prescribe an intraocular lens for an eye with a cornea disease or an eye having undergone a refraction correcting surgery, it is necessary to calculate the refractivity of the entire cornea by measuring the curvature radiuses of the anterior and posterior surfaces of the cornea of an eye to be examined, and the like. Japanese Patent Application Publication No. 2008-167777 discloses an ophthalmological device for examining the thickness of the cornea of an eye to be examined. The ophthalmological device in Japanese Patent Application Publication No. 2008-167777 includes an interference optical system, which radiates measurement light to an eye to be examined and detects interfering light composed of reflected light reflected from the eye to be examined and reference light which interfere with each other. The ophthalmological device detects the interfering light at a plurality of measurement points of the eye to be examined. Then, the position of the cornea's anterior surface and the position of the cornea's posterior surface at each measurement point are specified based on the interfering light detected at the plurality of measurement points. Thus, the thickness of the cornea at each measurement point of the eye to be examined is obtained.